Patho Chapter 34
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- What are the 2 groups of acids found in the body?
- 1. volatile acid - carbonic acid which is in equilibrium with CO2 2. fixed acids - like hydrocholirc, sulfuric, and phosphoric
- Carbon dioxide is transported in the circulation in these 3 forms:
- 1. attached to hemoglobin 2. dissolved CO2 in the plasma 3. as bicarbonate (HCO3)
- What enzyme generates carbonic acid from CO2 and water?
- carbonic anhydrase, which is present in RBCs and renal tubular cells
- Give 3 examples of intracellular and extracellular buffer systems used to regulate pH
- 1. proteins (such as albumin and gamma globulins 2. bicarbonate/CO2 buffer system 3. K+/H+ buffer system
- Generally, how do the kidneys regulate pH?
- - by excreting an acidic urine, the kidneys reduce the amount of acid in the extracellular fluid - by excreting an alkaline urine, the kidneys removes base from the extracellular fluid
- What are the kidney's effect on H+ and HCO3 when regulating pH?
- the kidney regulates pH by excreting excess H+ ions and reabsorbing or regenerating HCO3
- Where does most secretion of H+ and reabsorption of HCO3 take place?
- in the proximal convoluted tubule
- What is the anion gap?
- - the difference between the plasma concentration of the major measured cation (Na+) and the sum of the measured anions (Cl and HCO3) - this difference represents the concentration of unmeasured anions (such as phosphates, sulfates, organic acids, and proteins)
- What is the normal anion gap range?
- 8-12 mEq/L
- What conditions cause an increased anion gap?
- lactic acidosis and ketoacidosis (which result from elevated levels of metabolic acids)
- What conditions cause a low anion gap?
- - conditions that produce a fall in unmeasured anions or a rise in unmeasured cations - examples are hyperkalemia, hypercalcemia, hypermagnesemia, lithium intoxication, or multiple myeloma
- What is metabolic acidosis?
- a decrease in pH due to a decrease in bicarbonate
- How does the body compensate for metabolic acidosis?
- - increasing the respiratory rate in an effort to decrease CO2 - in the kidney, increased H+ excretion and increased bicarbonate reabsorption
- What are 4 mechanisms that can cause metabolic acidosis?
- 1. increased production of nonvolatile metabolic acids 2. decreased acid secretion by the kidney 3. excessive loss of bicarbonate 4. an increase in Cl-
- What is the respiratory compensatory mechanism for metabolic acidosis?
- - increasing ventilation to reduce PCO2 - done through deep and rapid respirations
- What is the renal compensatory mechanism for metabolic acidosis?
- - increase in H+ excretion - urine becomes more acidic
- What is metabolic alkalosis?
- an increase in pH due to increased bicarbonate levels
- Name 3 sources where most of the body's plasma bicarbonate comes from
- - from CO2 produced during metabolic processes - afrom reabsorption of filtered bicarbonate - generation of new bicarbonate by the kidney
- What is the respiratory compensation for metabolic alkalosis?
- hypoventilation to increase PCO2
- What is the renal compensatory mechanism for metabolic alkalosis?
- - decreased H+ excretion - decreased bicarbonate reabsorption
- What are some factors that maintain alkalosis?
- - decreased GFR - extracellular volume contraction - hypokalemia - hypochloremia - aldosterone excess
- What is respiratory acidosis?
- a decrease in pH, reflecting a decrease in ventilation, due to an increase in PCO2
- What are some causes of respiratory acidosis?
- - impaired ventilation as a result of decreased respiratory drive - lung disease - disorders of the chest wall and respiratory muscles - excess CO2 production
- What is hypercapnia?
- increased plasma PCO2
- What are the compensatory mechanisms for respiratory acidosis?
- - increased conservation and generation of bicarbonate - increased elimination of H+ by the kidney
- What is respiratory alkalosis?
- an increase in pH, resulting from an increase in alveolar ventilation, and a decrease in PCO2
- What is a cause of respiratory alkalosis?
- - hyperventilation
- True/False: Generally, neuromuscular excitability is decreased in acidosis
- In general, neuromuscular excitability is decreased in acidosis and increased in alkalosis The correct answer is: True